The emergence of multidrug resistant pathogens has become a substantial threat to treating infectious disease. Twenty percent of all deaths globally are the result of bacterial infections, and hospital-acquired infections are the sixth leading cause of mortality in the U.S., with 23 000 deaths per year due to multidrug resistant infections in the U.S. alone. Multidrug-resistant Gram-negative pathogens account for nearly 70% of infections in intensive care units in the U.S. Alarmingly, many Gram-negative clinical strains are becoming resistant to nearly all antibiotics, leaving few antibiotics in the therapeutic repertoire to treat these infections. Consequently, developing new compounds and combinations for the treatment of multidrug resistant pathogens is urgently required.